Numerical Analysis of Surface Tension Gradient Effect on the Behavior of Gas Bubbles at the Solid/Liquid Interface of Steel

Lee, Sang‐Min; Kim, Sang-Joon; Kang, Youn-Bae; Lee, Hae-Geon

doi:10.2355/isijinternational.52.1730

Cited by 14 publications

(6 citation statements)

References 22 publications

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“…Moreover, capture criteria mentioned previously can hardly explain the influence of superheat and sulfur content on the entrapment of inclusions. [282] For subsequent research, it is necessary to predict the inclusion distribution on the entire cross section of the slab and also include the influence of the instantaneous flow field, thermal transfer, solidification structure, solute transport, primary dendrite arm spacing, inclusion size, and forces acting on the inclusion. The motion of inclusions in CC strand is mainly controlled by the flow of the molten steel due to the micron scale of inclusions.…”

Section: Motion Removal and Entrapment Of Inclusions In CC Strandmentioning

confidence: 99%

Kinetic Modeling of Nonmetallic Inclusions Behavior in Molten Steel: A Review

Park

Zhang

2020

Metall Mater Trans B

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The kinetic modeling for the nucleation, size growth, and compositional evolution of nonmetallic inclusions in steel was extensively reviewed in the present article. The nucleation and initial growth of inclusion in molten steel during deoxidation as well as the collision growth, motion, removal, and entrapment of inclusions in the molten steel in continuous casting (CC) tundish and strand were discussed. Moreover, the recent studies on the prediction of inclusion composition in CC semiproducts were introduced. Since the 1990s, the development of thermodynamic model and relevant databases for inclusion engineering has been initiated by the steel industry. Later, the commercial software FACTSAGE employing the FACT database was widely used to predict the gas (atmosphere/bubble)-liquid (steel/slag/inclusion)-solid (refractory/slag/steel/inclusion) multiphase equilibria. With the help of the comprehensive thermodynamic database and solution models in conjunction with the development of user-friendly computing packages, the kinetics of inclusion evolution in molten steel can be successfully predicted based on several kinetic models such as the coupled reaction (CR) model, reaction zone model, and tank series recirculation (TSR) model. However, some parameters are needed to represent the real processes according to the model employed at different operational or experimental conditions. The effect of reoxidation on the evolution of inclusions in the ladle and tundish, which was experimentally confirmed, can be simulated by the effective equilibrium reaction zone (EERZ) model. The complex slag-steel interfacial reaction phenomena have been successfully explained by the interfacial kinetic model based on the dynamic interfacial tension and oxygen adsorption/desorption characteristics at the slag-steel interface.

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Section: Motion Removal and Entrapment Of Inclusions In CC Strandmentioning

confidence: 99%

Kinetic Modeling of Nonmetallic Inclusions Behavior in Molten Steel: A Review

Park

Zhang

2020

Metall Mater Trans B

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“…Particles larger than the PDAS are predicted to be engulfed only when they touch the dendritic interface and all of the forces acting on the particle are balanced [17,18]. The force balance includes the effect of surface tension gradient force, which pushes particles towards the solidification front [17][18][19][20]. This criterion has been validated with a benchmark experiment [21] and applied to accurately predict the capture of particles during steel continuous casting according to validation with several different sets of plant measurements [17,18,22,23].…”

Section: Introductionmentioning

confidence: 99%

Modeling of Inclusion Capture in a Steel Slab Caster with Vertical Section and Bending

Cho

Thomas

Hwang

et al. 2021

Metals

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Particles in molten steel, including argon-gas bubbles, slag droplets, and non-metallic inclusions, are removed into the surface-slag layer or captured by the solidifying steel-shell during continuous steel casting. Captured particles often become serious defects in the final steel product, so understanding particle-capture mechanisms is important for steel quality. Slab casters often have a straight mold and upper-strand prior to a curved lower-strand. The present work investigates particle capture in such a caster using computational modeling with a standard k-ε model for molten-steel flow, a discrete phase model for inclusion transport, and an advanced capture criterion for inclusion entrapment and engulfment into the steel shell. A new postprocessing methodology is presented and applied to predict inclusion-capture rates in commercial cast product. The locations and size distributions of particles captured into the shell, and actual capture rates are quantified. The model predictions are validated with ultrasonic-test plant measurements of the locations of large particles captured in a steel slab. The results reveal how large-inclusion capture accumulates in the beginning of the curved strand, leading to a capture band in the slab inside radius. Finally, the capture fractions and locations due to all capture mechanisms are compared for different inclusion sizes, and the implications are discussed.

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“…Small particles which contact the solidification front are easily entrapped between dendrites. On the other hand, large particles are only captured if the particle stays at the solidification front for long enough time to become surrounded by the growing shell front [82,94,[138][139][140]. A simple criterion, which captures any particle touching the solidifying shell, overpredicts the capture of large particles, as shown in Figure 22a.…”

Section: Double-ruler Embrmentioning

confidence: 99%

Electromagnetic Forces in Continuous Casting of Steel Slabs

Cho

Thomas

2019

Metals

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This paper reviews the current state of the art in the application of electromagnetic forces to control fluid flow to improve quality in continuous casting of steel slabs. Many product defects are controlled by flow-related phenomena in the mold region, such as slag entrapment due to excessive surface velocity and level fluctuations, meniscus hook defects due to insufficient transport of flow and superheat to the meniscus region, and particle entrapment into the solidification front, which depends on transverse flow across the dendritic interface. Fluid flow also affects heat transfer, solidification, and solute transport, which greatly affect grain structure and internal quality of final steel products. Various electromagnetic systems can affect flow, including static magnetic fields and traveling fields which actively accelerate, slow down, or stir the flow in the mold or strand regions. Optimal electromagnetic effects to control flow depends greatly on the caster geometry and other operating conditions. Previous works on how to operate electromagnetic systems to reduce defects are discussed based on results from plant experiments, validated computational models, and lab scale model experiments.

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Numerical Analysis of Surface Tension Gradient Effect on the Behavior of Gas Bubbles at the Solid/Liquid Interface of Steel

Cited by 14 publications

References 22 publications

Kinetic Modeling of Nonmetallic Inclusions Behavior in Molten Steel: A Review

Kinetic Modeling of Nonmetallic Inclusions Behavior in Molten Steel: A Review

Modeling of Inclusion Capture in a Steel Slab Caster with Vertical Section and Bending

Electromagnetic Forces in Continuous Casting of Steel Slabs

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